Fix is_generic

Author: Tinche

src/cattrs/_compat.py

@@ -411,8 +411,10 @@ def is_generic(type) -> bool:
     """Whether `type` is a generic type."""
     # Inheriting from protocol will inject `Generic` into the MRO
     # without `__orig_bases__`.
-    return isinstance(type, (_GenericAlias, GenericAlias)) or (
-        is_subclass(type, Generic) and hasattr(type, "__orig_bases__")
+    return (
+        isinstance(type, (_GenericAlias, GenericAlias))
+        or (is_subclass(type, Generic) and hasattr(type, "__orig_bases__"))
+        or type.__class__ is Union  # On 3.14, unions are no longer typing._GenericAlias
     )
 
 

src/cattrs/_generics.py

@@ -1,10 +1,10 @@
 from collections.abc import Mapping
-from typing import Any
+from typing import Any, get_args
 
 from attrs import NOTHING
 from typing_extensions import Self
 
-from ._compat import copy_with, get_args, is_annotated, is_generic
+from ._compat import copy_with, is_annotated, is_generic
 
 
 def deep_copy_with(t, mapping: Mapping[str, Any], self_is=NOTHING):